#top{width: 780px;
    height: 183px;
    background-color: aquamarine;
    margin-bottom: 2px;
}
#banner{width: 780px;
    height: 150px;
    background: url(../img/banner.jpg)no-repeat;
}
#nav li{width: 78px;
    height: 33px;
    float:left;
    text-align: center;
    
    line-height: 33px;
}
#nav a{background: url(../img/button1.jpg);
    display: block;
    
}
#nav a:hover{background: url(../img/button1_bg.jpg);
    position: relative;
    top: 1px;
    left: 1px;
}
#nav ul{list-style: none;}